Path: csiph.com!eternal-september.org!feeder.eternal-september.org!nntp.eternal-september.org!.POSTED!not-for-mail From: Lynn Wheeler Newsgroups: alt.folklore.computers Subject: Re: CMS, Self-hosting and the 6502 Date: Sun, 05 Apr 2026 22:19:00 -1000 Organization: Wheeler&Wheeler Lines: 28 Message-ID: <87pl4c1oy3.fsf@localhost> References: <10qehuo$2nu4m$1@dont-email.me> <87h5pqwd5j.fsf@localhost> <10qs7og$129km$4@dont-email.me> <10qt6h6$19mab$1@dont-email.me> <10qucqd$cs9$2@gal.iecc.com> <10qv31u$1l5fk$3@paganini.bofh.team> <10qv7t7$1re07$2@dont-email.me> <10qvlrb$1uf62$2@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Date: Mon, 06 Apr 2026 08:19:04 +0000 (UTC) Injection-Info: dont-email.me; posting-host="5a5b7f1cc9e89257f9f881ec8e8a482f"; logging-data="2078498"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18iGhXWUakwFl+pnDRdN4T5Un6lDLkGFto=" User-Agent: Gnus/5.13 (Gnus v5.13) Cancel-Lock: sha1:4fQuwJoYR9IXcmrwpIgXs1GEYJA= sha1:2AUqxCCjlGS/Sjk4uxAhh8hA5MQ= Xref: csiph.com alt.folklore.computers:234628 Lawrence D’Oliveiro writes: > Did it really take that many decades for IBM to understand the concept > of position-independent code? TSS/360 supported position independent code .... could have same shared segments across different virtual address spaces at different address locations. OS/360 languages generated executable with "relocatable" addresses and loader, loading the executable images when loaded, the relocable addresses were updated for the ("fix") loaded address locations (aka "relocatable" until loaded for execution). after joining IBM CSC ... with competition from TSS/360 and MULTICS up on the 5th flr ... I did a page-mapped filesystem for CP67's CMS (nominal filesystem workload about 3times faster (and degrading much more gracefully as load increased) and since CMS used OS/360 language processors ... it had fixed addresses as part of loading. I had to do a lot of code fiddling in order to emulate TSS/360 being able to load shared segments at independent locations. With TSS/360 decommitted and all the 360 systems (MVT, MFT, DOS) having to support 370 virtual memory .... the wide-spread implementation of the "relocatable addresses" updating to correspond to the loaded address ... sort of negated any position-independent orientation. -- virtualization experience starting Jan1968, online at home since Mar1970